Abrasive wheel



H. L. HARVEY ABRASIVE WHEEL.

Aug. 28, 1956 Filed May 12 LONG? FIBERED' PAPER SPIRA LLY LAID CORD ABRASIVE GRITS IN BINDER ABRASIVE WHEEL Howard L. Harvey, Haddonfield, N. J., assignor to American Viscose Corporation, Philadelphia, Pa.,- a corporation of Delaware Application May 12, 1955, Serial 'No. 507,786

11 Claims. (Cl. 51-209) This invention relates to abrasive wheels and discs and a method of making such articles and, more particularly, to reinforced abrasive wheels and discs.

The present application is a continuation in part of my abandoned application, Serial No. 498,586, filed April 1, 1955.

Abrasive Wheels and discs have been produced having a textile fabric reinforcement on one or both sides of the wheel or disc bonded to the body which consists of a molded mass of a binding material and the abrasive particles with or withoutadditional strengthening materials and fillers, such as fibers and chopped rag. Because of the inherent nature of knitted and woven textile fabrics, the strength of the molded wheel or disc varied in different radial directions. A further disadvantage in wheels and discs of this type is that upon wearing of the grinding edge, the woven fabrics often leave a ragged edge.

The principal purpose of the present invention is to provide a grinding wheel or disc which has a substantially uniform strength in all radial directions.

Another purpose of the present invention is to provide a grinding wheel which will continuously present a smooth grinding surface as the wheel becomes worn.

.A still further object of the invention is to provide a grinding disc having a reinforced construction of suflicient strength to prevent parts of the disc from breaking off even when the grinding face is fractured.

Other objects and advantages of this invention will become apparent from the following description and claims.

In the drawings:

Figure 1 is a transverse section of a grinding disc constructed in accordance with the present invention; and

Figure 2 is a back View of the disc of Figure 1 with the structure broken away and the spiral element exaggerated to more clearly illustrate its construction.

Figure 3 is a fragmentary detail of a grinding disc constructed in accordance with the present invention 7 showing how the backing paper and the cord retain any pieces of the grinding face which may become fractured; and

Figure 4 is an enlarged sectional detail as seen at IVIV of Figure 3.

The present invention is a continuation-in-part of United States patent application 498,586, filed on April 1, 1955, and contemplates an abrasive wheel or disc reinforced with a spirally laid cordand a long fibered paper which are bonded together, as by stitching, and bonded to the abrasive material.

Referring more particularly to the drawings, the present grinding disc has a centrally perforated backing sheet or disc 1 of a latex impregnated long fibered paper. This paper is rigidly adhered or stitched to a spiral layer of cord 2 which is preferably laid on the paper in close convolutions. The abrasive grinding face 3 is likewise bonded to the layer of cord and comprises suitable grits in a binder. The disc is provided with the customary offset hub 4 having a bore 5 for mounting on the grinder spindle} The elements of the wheel when finished form a unitary tough structure which cannot be fractured into small pieces under any conditions of use or even abuse.

The longfibered paper is preferably a paper formed of fibers having the length of from four to seven millimeters and the fibers have diameters of from seventeen to twentyfive microns. The paper is preferably formed Without sizing and is impregnated with latex, either a synthetic or natural elastomeric material dispersion. The paper may be formed of hemp or abaca fibers and may contain from about to about by weight of the latex. Paper, such as described in Patent No. 2,541,763 has been found to be very satisfactory for the purposes of this invention. Silicone rubbers may also be used to impregnate the long fibered paper.

The spirally laid cord may be formed of any desired fibrous strand, such as cotton, rayon, nylon, or other synthetic fibers such as Dacron, Acrilan, Orlon and the like. The size or diameter of the cord or strand may be selected to provide the desired reinforcement. For example, it may be varied in diameter depending upon the thickness of the grinding wheel or disc and the speed at which the grinding disc will be operated. The cord may be impregnated with or treated with a thermos etting resin, as for example urea-formaldehyde, melamine-formaldehyde, and phenol-formaldehyde in the thermoplastic state and containing a latent curing catalyst, either before or after it is disposed'in the spiral position.

The abrading element 3 is of any desired composition. The active abrasive material may consist of any desired abrasive grit or grain, such as aluminum oxide, silicone carbide, boron carbide, diamonds, emery and the like.

The size of the abrasive particles and the particle size,

dehyde resins, urea-formaldehyde resins, melamine-formaldehyde resins and other amino triazine resins. The abrasive element may be formed in any desired manner as by mixing the abrasive grits or grains with the powdered resinoid or the abrasive grits may be first coated with the resinoid'and then mixed with additional quantities of the bonding material. The abrasive grits may be coated with a specific bonding material and the bulk of the bonding material may consist of a difierent specific material. For example, the abrasive grits may be wet with a phenolic condensation product and the coated grits then mixed with an amino triazine aldehyde condensation product and the mixture subsequently molded.

Fillers or substances and materials to strengthen or improve the impact resistance of the abrading element may be incorporated in the mix prior to molding to shape. for example, fibers of various lengths or' chopped rag formed of either natural or synthetic fibers may be in corporated in the mixture to improve the impact resistance and fiexural strength of the abrading element. These types of filler materials may be impregnated with a resinoid material to insure a thorough bonding between the constituents of the abrading element. Other fillers, such as clay, asbestos fiber, mica or other materials commonly used in abrading elements may also be present.

Patented Aug. 28, 6

arreo sis It is apparent that the specifie constituents and the rela tive proportions of the various constituents will be deter- I .mined by the intended use of any specific grinding wheel. f The composition of the abrading element'doesfnot form a. part of the present invention; However,. the present inyentionis. applicable. to any and allv abrading. wheels f and discs. wherein the abrading element contains a; bonds ing materialv which maybe bonded to? the spirally'laid' cord reinforcement.

. In. formingthe. grinding wheels ondiscs. in. accordance with this invention, the. impregnated. long bered paper disc. is held at, its center opening in, a manner soas. to permit it to be moved concomitantly in rotary and side.- .WiseI directions. A cord or strand- 2;mayhe adhesively secured to the paper disc 1 butin: the; preferred form qof the, invention. the cord 2. is laid on the paper; disc 1 irra, spiral. manner and held-fin place, by a light thread stitchedqas seen at 6 in Fig; 2., For the sake of clarity and simplicity, only a smallpoi tion; of the stitching has been illustrated. on the drawing, it. being understoodthat a1l..con.volutions of the card are secured. to the. paper; discby stitching. As described-above the cord or'strand 2 is-impregnated with a'thermosetting resin, for example, I a, rayoncord such as conventionally employed in the manufacture of tire casings may be impregnated with a phenolic resin. and laid on the paper: disc withoutconyerting the. resin to its thermoset' condition. 'By securing the-reinforcing cord 2. to the paper disc as. set forth above,

the spiral cord formation and the paper disc itself are better able to. retain'their original and intended shapes during molding. The paper disc, with the cord secured ;thereto; is placed in .the'mold and the abrading material,

either in'the form of a powder or granular mix or in the the wheel without flying apart. Comparable grinding; wheels having nylon and glass fiber textile reinforcing etc ments or discs when operated under the same conditions have generally been found to fly apart upon fracture of the abrading element. It has also been found that as the grinding surface becomes worn down, theperipheral edge of the spirally laid cord and the paper: become. worn away without. leaving a ragged edge as'is' so common in the case of '10 theusual textile reinforcing elements. 7, e

In forming the gninding wheei as describedi above and utilizing pressures exceeding about 3000=pounds per-square inch, the reinforc ngiclement-appearsto be aunitany body form of a. preformed disc containing the thermosetting resin. in "a thermoplastic condition,'is. then placed over the-spirally. laid cord. The mold is. then closed and the laminated body. subjected to the. required pressures and temperatures whereby the elements. become bonded together to form a unitary body. The, wheel-or disc which is formedrnay be employed as a grinding Wheel or a.

grinding disc, 7 V

During the molding operation, the stitching thread holding the'spiral'cord formation on' the paper disc 1 is subjected to high temperature and pressures of approximately 3,000: pounds per square inch. and therefore have iatendencytoibreak. However; once the molding operation is. underway, the stitching has already served its' purp se andrthe broken. threads: in no. way impair the a that textilefabrics impregnated with phenolicresins and used as reinforcing elements in'grinding wheels areexf orcing element. readily cracks and if the grinding wheel is operatingat a high speed, the wheel will fly apart. Wheels of the present invention, although they have element through its entire thickness, have been. operated at speeds far inexcess of the normal operating speed for wherein the paper disc and spirally 'laid cordareso thoroughly bonded togetherthat -it is diflicult to distinguish between the two elements. The strengthof the wheel and the characteristic ofthefractured wheel of being. capable. of withstanding, excessive speedsv is. not-obtainable. by the. use of either a, spirally laidcord. ora Long;

fibered paper. that these. characteristics are. obtained;

I Claim; v V

' Il. In a grinding wheel a reinforcing element compris- 7 ing a long. tibcrcd'paper and, a; spirally laid cord; the

paper and the cord being combined into an integral body.

. ZQAreihforcingelement as definedin claiml wherein the. paper. is. formed of. abaca. fibers.

3., Areinforcing'element as defined inclaim l'wherein the cord' is formedjof rayon,

4. A reinforcingelement as defined in claim 1 wherein the paper is. formed of abaca fibers and isimpreguatedf with. a latex and the'cord is formed of rayon impregnated with a phenolic condensation product.

. 5.. A construction. as defined incl'aim' l 'wherein 'said paper and. cord are combined bystitching.

6. The method of forminga grindingwheel which c'ogmrises sewing a. spirallyllaidgcord .to a long fibere'd paper, positioning the combined paper and cord in amold'ppl acing an abrading composition over the spirally laidcord and applying heat and pressure'to bond the paper, cord and abrasive composition together to. form a'unitary body;

71A non-fracturabl'e grinding wheel having aback-. ingv sheet offiong fiberedf latex impregnated; paper, a sP Ial cord' to which said. backing sheet is bonded; and a...

grinding face of abrasive grits bonded to said cord",

8. A grinding wheel in a'ccordancewith clairnT'in which: the longv fibers are abaca.

9; A grinding wheelj comprising an abradingldisc' have ingon. at least one of its sides a reinforcing elementcom V prising a spirally laid cord bonded tothe, abrasfiveele- 'ment and a, long fibered paper bonded tothespirally laidf; f cord. 1 It). 'A grinding wheel in accordance with claim 2hr which the paper and cord are bonded by stitching.

. 11- h me od of ormin a r n ing, wheeljw if h comprises positioning a long fib ered paper in amolgl,

ceedinglybrittley I-f'a grinding wheel having such reinforcement is accidentally subjected to a blow, the reinbeen. subjected to a. blow sufficient to crack the abrading disposing spirally. laid cord over the-paper in the mold; placing an abrading 'c'omposition over the spirallylaid cord and applying heat and pressure to, bond the paper,

cord. and abrasivecomposition together 'to form a unitary,

body. I

References Citedin the file. of this patent- UNITED STATES PATENTS 2,260,941 Hendrickson 'Oct: 28,. .1941

It is. only by the. combinationz of. the.- two 

1. IN A GRINDING WHEEL A REINFORCING ELEMENT COMPRISIN A LONG FIBERED PAPER AND A SPRIRALLY LAID CORD, THE PAPER AND THE CORD BEING COMBINED INTO AN INTEGRAL BODY. 